Fix findings

spec/marten/core/sluggable_spec.cr

@@ -0,0 +1,54 @@
+require "./spec_helper"
+
+describe Marten::Core::Sluggable do
+  describe ".generate_slug" do
+    value = "Test Title 123"
+    max_size = 20
+    slug = Marten::Core::Sluggable.generate_slug(value, max_size)
+
+    it "removes non-alphanumeric characters" do
+      value_with_special_chars = "Test@Title#123!"
+      slug = Marten::Core::Sluggable.generate_slug(value_with_special_chars, max_size)
+      slug.starts_with?("testtitle12-").should be_true
+    end
+
+    it "converts the string to lowercase" do
+      slug.starts_with?("testtitle12-").should be_true
+    end
+
+    it "replaces whitespace and hyphens with a single hyphen" do
+      value_with_spaces_and_hyphens = "Test - Title   123"
+      slug = Marten::Core::Sluggable.generate_slug(value_with_spaces_and_hyphens, max_size)
+      slug.starts_with?("test-title-").should be_true
+    end
+
+    it "strips leading and trailing hyphens and underscores" do
+      value_with_hyphens = "-Test Title 123-"
+      slug = Marten::Core::Sluggable.generate_slug(value_with_hyphens, max_size)
+      slug.starts_with?("test-title-").should be_true
+    end
+
+    it "removes non-ASCII characters" do
+      value_with_non_ascii = "Test Títle 123"
+      slug = Marten::Core::Sluggable.generate_slug(value_with_non_ascii, max_size)
+      slug.starts_with?("test-ttle-1-").should be_true
+    end
+
+    it "limits the slug length to max_size" do
+      slug.size.should eq(max_size)
+    end
+
+    it "does not exceed max_size even with long input" do
+      long_value = "This is a very long title that should be truncated"
+      slug = Marten::Core::Sluggable.generate_slug(long_value, max_size)
+      slug.size.should eq(max_size)
+    end
+
+    it "does not truncate the slug when max_size is large enough" do
+      long_value = "This is a very long title that should not be truncated"
+      slug = Marten::Core::Sluggable.generate_slug(long_value, 100)
+
+      slug.starts_with?("this-is-a-very-long-title-that-should-not-be-truncated").should be_true
+    end
+  end
+end

spec/marten/db/field/slug_spec.cr

@@ -111,14 +111,6 @@ describe Marten::DB::Field::Slug do
 
       article.slug.not_nil!.should eq("custom-slug")
     end
-
-    it "uses a custom slug generator function when provided" do
-      article = Marten::DB::Field::SlugSpec::ArticleWithCustomSlugGenerator.new(title: "My First Article")
-
-      article.save
-
-      article.slug.not_nil!.should eq("MY_FIRST_ARTICLE")
-    end
   end
 
   describe "#validate" do

src/marten/core/sluggable.cr

@@ -0,0 +1,31 @@
+module Marten
+  module Core
+    # The Sluggable module provides functionality for generating URL-friendly slugs from strings.
+    module Sluggable
+      extend self
+
+      NON_ALPHANUMERIC_RE  = /[^\w\s-]/
+      WHITESPACE_HYPHEN_RE = /[-\s]+/
+      NON_ASCII_RE         = /[^\x00-\x7F]/
+
+      # Generates a slug from the given value, ensuring the resulting slug does not exceed the specified max_size.
+      #
+      # The slug is created by:
+      # 1. Removing non-alphanumeric characters (except whitespace and hyphens).
+      # 2. Converting the string to lowercase.
+      # 3. Replacing sequences of whitespace and hyphens with a single hyphen.
+      # 4. Removing non-ASCII characters.
+      # 5. Truncating the slug to fit within the max_size, minus the size of a randomly generated suffix.
+      # 6. Stripping trailing hyphens and underscores of the slug without suffix, and appending the suffix.
+      def generate_slug(value, max_size)
+        suffix = "-#{Random::Secure.hex(4)}"
+
+        slug = value.gsub(NON_ALPHANUMERIC_RE, "").downcase
+        slug = slug.gsub(WHITESPACE_HYPHEN_RE, "-")
+        slug = slug.gsub(NON_ASCII_RE, "")
+
+        slug[...(max_size - suffix.size)].strip("-_") + suffix
+      end
+    end
+  end
+end

src/marten/db/field/base.cr

@@ -86,11 +86,8 @@ module Marten
         def perform_validation(record : Model)
           value = record.get_field_value(id)
 
-          if value.nil? && !@null
-            record.errors.add(id, null_error_message(record), type: :null)
-          elsif empty_value?(value) && !@blank
-            record.errors.add(id, blank_error_message(record), type: :blank)
-          end
+          validate_null(record, value)
+          validate_blank(record, value)
 
           validate(record, value)
         end
@@ -147,6 +144,18 @@ module Marten
         def validate(record, value)
         end
 
+        protected def validate_null(record : Model, value)
+          if value.nil? && !@null
+            record.errors.add(id, null_error_message(record), type: :null)
+          end
+        end
+
+        protected def validate_blank(record : Model, value)
+          if empty_value?(value) && !@blank
+            record.errors.add(id, blank_error_message(record), type: :blank)
+          end
+        end
+
         # :nodoc:
         macro check_definition(field_id, kwargs)
         end

src/marten/db/field/slug.cr

@@ -5,11 +5,7 @@ module Marten
     module Field
       # Represents a slug field.
       class Slug < String
-        NON_ALPHANUMERIC_RE  = /[^\w\s-]/
-        WHITESPACE_HYPHEN_RE = /[-\s]+/
-
         private getter slugify
-        private getter slugify_cb
 
         def initialize(
           @id : ::String,
@@ -21,13 +17,8 @@ module Marten
           @unique = false,
           @index = true,
           @db_column = nil,
-          @slugify : Symbol? = nil,
-          @slugify_cb : (::String -> ::String) = ->(value : ::String) { generate_slug(value) }
+          @slugify : Symbol? = nil
         )
-          if @slugify
-            @null = true
-            @blank = true
-          end
         end
 
         macro check_definition(field_id, kwargs)
@@ -36,9 +27,8 @@ module Marten
 
         def validate(record, value)
           if slugify?(value)
-            slug = slugify_cb.call(record.get_field_value(slugify.not_nil!).to_s)
+            slug = Core::Sluggable.generate_slug(record.get_field_value(slugify.not_nil!).to_s, max_size)
             record.set_field_value(id, slug)
-            return
           end
 
           return if !value.is_a?(::String)
@@ -51,14 +41,12 @@ module Marten
           end
         end
 
-        private def generate_slug(value)
-          suffix = "-#{Random::Secure.hex(4)}"
-
-          slug = value.gsub(NON_ALPHANUMERIC_RE, "").downcase
-          slug = slug.gsub(WHITESPACE_HYPHEN_RE, "-").strip("-_")
-          slug = slug.gsub(/[^\x00-\x7F]/, "")
+        protected def validate_null(record : Model, value)
+          super if slugify.nil?
+        end
 
-          slug[...(max_size - suffix.size)] + suffix
+        protected def validate_blank(record : Model, value)
+          super if slugify.nil?
         end
 
         private def slugify?(value)